Ink jet ink composition, ink set and ink jet treatment liquid, and ink jet recording method and ink jet recording apparatus using the same

ABSTRACT

The present invention provides an ink jet ink composition containing at least water, a colorant and a water soluble organic solvent. The ink jet ink composition contains at least one amine compound represented by the following formula (1) in a range of 10 to 30% by mass:  
                 
 
     wherein the amine compound represented by the formula (1) is any one of primary to tertiary amine compounds; at least one of three substituents represented by R 1 , R 2  and R 3  in the formula (1) comprises a hydrocarbon group having a hydroxyl group; and none of the three substituents contain an alkyl group having at its terminal either one of —CO 2 M and —SO 3 M in which M represents an atom or an atomic group selected from hydrogen, an alkali metal, an alkaline earth metal, an ammonium group and an organic amine group.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority under 35 USC 119 from JapanesePatent Application No. 2003-111260, the disclosure of which isincorporated by reference herein.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an ink jet ink composition, anink-set and an ink jet treatment liquid which are used for an ink jetrecording apparatus (e.g., a printer, a copier, a facsimile, or a wordprocessor), and an ink jet recording method and an ink jet recordingapparatus which use the ink jet ink composition, the ink-set and the inkjet treatment liquid.

[0004] 2. Description of the Related Art

[0005] A so-called ink jet recording apparatus in which a liquid or amolten solid ink is ejected through a nozzle, slit, porous film or thelike to record onto paper, cloth, film, or the like has variousadvantages such as being compact, inexpensive and quiet. Many kinds ofthese recording apparatuses including not only monochrome printers, butalso color printers capable of recording full-color images, with which agood quality is obtained on plain paper such as report paper, copypaper, or the like, have been recently sold in the market, and therebyoccupy a large share for the market of recording apparatus. Among theseink jet recording apparatuses, so-called piezo inkjet printers usingpiezoelectric elements, and so-called thermal ink jet recordingapparatuses which use heat energy to form droplets and then print havevarious advantages such as high printing speed and high resolution.

[0006] The ink used in the ink jet recording apparatus mainly contains asolvent, a colorant and additives. The following characteristics arerequired for the ink jet recording ink: that the ink can provideuniform, blotting-free and fog-free images with high resolution and highdensity; that the ink causes no clogging at the tip of the nozzle due todried ink and always exhibits good ejecting responsiveness and goodejecting stability; that the ink rapidly dries on paper; that the inkhas good image fastness; and the ink has good long-term storagestability.

[0007] In addition, there is a need for an ink having characteristicssuch that it relieves or suppress a noticeable incidence of curling of arecording medium such as regular paper. Curl refers to a phenomenon inwhich a recording medium becomes rounded during or after printing.

[0008] The curled recording medium is quite inconvenient since therecording medium cannot be piled or spread out into a sheet. Curl of thesheet is particularly a problem when color graphic images having manysolid printing portions are continuously printed at a high speed.Moreover, since curl makes it difficult to print on both faces, it isnecessary to suppress and relieve curling of recording media for thisreason as well.

[0009] It has been proposed to use 1,3-diols, 1,3,5-triols andamino-1,3-diols as anti-curl agents in the ink in order to suppresscurling (see Japanese Patent Application Laid-Open (JP-A) No. 6-157955).Adding amide compounds in the ink as the anti-curl agent has been alsoproposed (see JP-A No. 9-176538). Adding hydroxyamide derivatives in theink as the anti-curl agent has been further proposed (see JP-A No.10-204348).

[0010] However, although these methods can suppress curling, a largequantity of the anti-curl agent must be added in he ink to suppresscurling. Accordingly, the ink in which a large quantity of the anti-curlagent is added causes insufficient image quality, clogging of nozzles,lower apparatus reliability, and the like. Thus, these methods are notsufficient.

[0011] Some techniques for suppressing curl by treating a recordingmedium have been proposed. For example, a method in which a back-coatlayer is provided at a surface opposite from an ink receiving layer ofthe recording medium (see JP-A No. 8-310111) has been proposed. Also, ithas been proposed to use a regular paper type recording medium in whichirreversible shrinkage factors of the paper in a machine direction (MD)and a cross direction (CD) when the relative humidity is changed arecontrolled (see JP-A No. 9-234946). A method for controlling the degreeof curl size of a coating layer and a surface opposite from the coatinglayer has been further proposed (see JP-A No. 10-278413).

[0012] However, although some effects of improving curl is obtained withthese conventional techniques, these are not sufficient. Since users arerequired to purchase recording media treated with the anti-curl agent,convenience for general users is compromised. Considering userconvenience, an ink that is able to prevent curling when any recordingmedia is used for printing is more convenient and more desired than therecording medium treated with the anti-curl agent.

SUMMARY OF THE INVENTION

[0013] The present invention has been made in view of the abovecircumstances. First, the invention is to provide an ink jet inkcomposition, an ink set, an ink jet treatment liquid, an ink jetrecording method and an ink jet recording apparatus that can relieve orsuppress curling of the recording medium and clogging of nozzles.

[0014] Secondly, the invention is to provide an ink jet ink composition,an ink set, an ink jet treatment liquid, an ink jet recording method andan ink jet recording apparatus that can relieve or suppress curling ofthe recording medium and clogging of nozzle, as well as further improveimage density.

[0015] The inventor of the invention has investigated the mechanism bywhich curl occurs.

[0016] In general, curl is believed to occur due to permeation of watercontained in the ink among cellulose fibers in the recording mediumduring printing and breaking of hydrogen bonds among the fibers by thepermeated water. While the hydrogen bonds broken by water in the inkreform as the water is evaporated, the hydrogen bonds are formed amongcloser hydroxyl groups. Consequently, cellulose fibers are rearranged toshorten the distances among the cellulose fibers, whereby the entirerecording medium shrinks.

[0017] The ink is usually ejected to print on one surface of therecording medium during printing in the ink jet recording apparatus.Since the recording medium is shrunk only on its printed surface, it ispresumed that a difference in shrinkage factor is caused between theprinted surface and the non-printed surface, whereby the recordingmedium curls.

[0018] A first aspect of the invention is to provide an ink jet inkcomposition comprising at least water, a colorant and a water-solubleorganic solvent, wherein the ink jet ink composition comprises at leastone amine compound represented by the following formula (1) in a rangeof 10 to 30% by mass:

[0019] wherein the amine compound represented by the formula (1) is anyone of primary to tertiary amine compounds; at least one of threesubstituents represented by R₁, R₂ and R₃ in the formula (1) comprises ahydrocarbon group having a hydroxyl group; and none of the threesubstituents contain an alkyl group having at its terminal either one of—CO₂M and —SO₃M in which M represents an atom or an atomic groupselected from hydrogen, an alkali metal, an alkaline earth metal, anammonium group and an organic amine group.

[0020] A second aspect of the invention is to provide an ink jet inkcomposition comprising at least water, a colorant and a water-solubleorganic solvent, wherein the ink jet ink composition comprises at leastone amine compound represented by the following formula (2):

[0021] wherein the amine compound represented by the formula (2) is anyone of primary to tertiary amine compounds; at least one of threesubstituents represented by R₁′, R₂′ and R₃′ in the formula (2)comprises a hydrocarbon group having a hydroxyl group; and at least oneof the three substituents comprises a hydrocarbon group containing analkyl group having at its terminal either one of —CO₂M and —SO₃M inwhich M represents an atom or an atomic group selected from hydrogen, analkali metal, an alkaline earth metal, an ammonium group and an organicamine group.

[0022] A third aspect of the invention is to provide an ink jetrecording method comprising forming an image by adhering an ink jet inkcomposition comprising at least water, a colorant and a water solubleorganic solvent, to a recording medium, wherein the ink jet inkcomposition comprises at least one amine compound represented by thefollowing formula (1) in a range of 10 to 30% by mass:

[0023] wherein the amine compound represented by the formula (1) is anyone of primary to tertiary amine compounds; at least one of threesubstituents represented by R₁, R₂ and R₃ in the formula (1) comprises ahydrocarbon group having a hydroxyl group; and none of the threesubstituents contain an alkyl group having at its terminal either one of—CO₂M and —SO₃M in which M represents an atom or an atomic groupselected from hydrogen, an alkali metal, an alkaline earth metal, anammonium group and an organic amine group.

[0024] A fourth aspect of the invention is to provide an ink jetrecording method comprising forming an image by adhering an ink jet inkcomposition comprising at least water, a colorant and a water solubleorganic solvent, to a recording medium, wherein the ink jet inkcomposition comprises at least one amine compound represented by thefollowing formula (2):

[0025] wherein the amine compound represented by the formula (2) is anyone of primary to tertiary amine compounds; at least one of threesubstituents represented by R₁′, R₂′ and R₃ in the formula (2) comprisesa hydrocarbon group having a hydroxyl group; and at least one of thethree substituents comprises a hydrocarbon group containing an alkylgroup having at its terminal either one of —CO₂M and —SO₃M in which Mrepresents an atom or an atomic group selected from hydrogen, an alkalimetal, an alkaline earth metal, an ammonium group and an organic aminegroup.

[0026] A fifth aspect of the invention is to provide an ink jetrecording apparatus comprising at least a recording head including aliquid ejection surface having a nozzle for ejecting a liquid, and arecording medium transfer section for transferring a recording medium inone direction while the recording medium faces the liquid ejectionsurface and a shortest distance between the recording medium and theliquid ejection surface is constantly maintained, wherein:

[0027] during printing,an image is formed by ejecting the liquid onto asurface of the recording medium from the liquid ejection surface whilemoving the recording head in a direction substantially perpendicular tothe transfer direction of the recording medium;

[0028] an ink jet ink composition comprising at least water, a colorantand a water soluble organic solvent is used as the liquid; and

[0029] the ink jet ink composition comprises at least one amine compoundrepresented by the following formula (1) in a range of 10 to 30% bymass,

[0030] wherein the amine compound represented by the formula (1) is anyone of primary to tertiary amine compounds; at least one of threesubstituents represented by R₁′, R₂ and R₃ in the formula (1) comprisesa hydrocarbon group having a hydroxyl group; and none of the threesubstituents contain an alkyl group having at its terminal either one of—CO₂M and —SO₃M in which M represents an atom or an atomic groupselected from hydrogen, an alkali metal, an alkaline earth metal, anammonium group and an organic amine group.

[0031] A sixth aspect of the invention is to provide an ink jetrecording apparatus comprising at least a recording head including aliquid ejection surface having a nozzle for ejecting a liquid, and arecording medium transfer section for transferring a recording medium inone direction while the recording medium faces the liquid ejectionsurface and a shortest distance between the recording medium and theliquid ejection surface is constantly maintained, wherein:

[0032] during printing, an image is formed by ejecting the liquid onto asurface of the recording medium from the liquid ejection surface whilemoving the recording head in a direction substantially perpendicular tothe transfer direction of the recording medium;

[0033] an ink jet ink composition comprising at least water, a colorantand a water soluble organic solvent is used as the liquid; and

[0034] the ink jet ink composition comprises at least one amine compoundrepresented by the following formula (2),

[0035] wherein the amine compound represented by the formula (2) is anyone of primary to tertiary amine compounds; at least one of threesubstituents represented by R₁′, R₂′ and R₃′ in the formula (2)comprises a hydrocarbon group having a hydroxyl group; and at least oneof the three substituents comprises a hydrocarbon group containing analkyl group having at its terminal either one of —CO₂M and —SO₃M inwhich M represents an atom or an atomic group selected from hydrogen, analkali metal, an alkaline earth metal, an ammonium group and an organicamine group.

[0036] A seventh aspect of the invention is to provide an ink setcomprising at least two inks which each comprise water, a colorant and awater soluble organic solvent, wherein at least one ink in the ink setcomprises at least one amine compound represented by the followingformula (1) in a range of 10 to 30% by mass:

[0037] wherein the amine compound represented by the formula (1) is anyone of primary to tertiary amine compounds; at least one of threesubstituents represented by R₁, R₂ and R₃ in the formula (1) comprises ahydrocarbon group having a hydroxyl group; and none of the threesubstituents contain an alkyl group having at its terminal either one of—CO₂M and —SO₃M in which M represents an atom or an atomic groupselected from hydrogen, an alkali metal, an alkaline earth metal, anammonium group and an organic amine group.

[0038] An eighth aspect of the invention is to provide an ink setcomprising at least two inks which each comprise water, a colorant and awater soluble organic solvent, wherein at least one ink in the ink setcomprises at least one amine compound represented by the followingformula (2):

[0039] wherein the amine compound represented by the formula (2) is anyone of primary to tertiary amine compounds; at least one of threesubstituents represented by R₁′, R₂′ and R₃′ in the formula (2)comprises a hydrocarbon group having a hydroxyl group; and at least oneof the three substituents comprises a hydrocarbon group containing analkyl group having at its terminal either one of —CO₂M and —SO₃M inwhich M represents an atom or an atomic group selected from hydrogen, analkali metal, an alkaline earth metal, an ammonium group and an organicamine group.

[0040] A ninth aspect of the invention is to provide an ink jetrecording method comprising forming an image by using an ink setcontaining at least two inks comprising at least water, a colorant and awater soluble organic solvent, and by adhering an ink of the ink set toa recording medium, wherein at least one ink of the ink set comprises atleast one amine compound represented by the following formula (1) in arange of 10 to 30% by mass:

[0041] wherein the amine compound represented by the formula (1) is anyone of primary to tertiary amine compounds; at least one of threesubstituents represented by R₁, R₂ and R₃ in the formula (1) comprises ahydrocarbon group having a hydroxyl group; and none of the threesubstituents contain an alkyl group having at its terminal either one of—CO₂M and —SO₃M in which M represents an atom or an atomic groupselected from hydrogen, an alkali metal, an alkaline earth metal, anammonium group and an organic amine group.

[0042] A tenth aspect of the invention is to provide an ink jetrecording method comprising forming an image by using an ink setcontaining at least two inks comprising at least water, a colorant and awater soluble organic solvent, and by adhering an ink of the ink set toa recording medium, wherein at least one ink of the ink set comprises atleast one amine compound represented by the following formula (2):

[0043] wherein the amine compound represented by the formula (2) is anyone of primary to tertiary amine compounds; at least one of threesubstituents represented by R₁′, R₂′ and R₃′ in the formula (2)comprises a hydrocarbon group having a hydroxyl group; and at least oneof the three substituents comprises a hydrocarbon group containing analkyl group having at its terminal either one of —CO₂M and —SO₃M inwhich M represents an atom or an atomic group selected from hydrogen, analkali metal, an alkaline earth metal, an ammonium group and an organicamine group.

[0044] An eleventh aspect of the invention is to provide an ink jetrecording apparatus comprising at least a recording head including aliquid ejection surface having at least two nozzles for independentlyejecting at least two liquids, and a recording medium transfer sectionfor transferring a recording medium in one direction while the recordingmedium faces the liquid ejection surface and a shortest distance betweenthe recording medium and the liquid ejection surface is constantlymaintained, wherein:

[0045] during printing, an image is formed by ejecting the at least twoliquids onto a surface of the recording medium from the liquid ejectionsurface while moving the recording head in a direction substantiallyperpendicular to the transfer direction of the recording medium;

[0046] an ink set comprising at least two inks comprising at leastwater, a colorant and a water soluble organic solvent is used as the atleast two liquids; and

[0047] at least one ink in the ink set comprises at least one aminecompound represented by the following formula (1) in a range of 10 to30% by mass,

[0048] wherein the amine compound represented by the formula (1) is anyone of primary to tertiary amine compounds; at least one of threesubstituents represented by R₁, R₂ and R₃ in the formula (1) comprises ahydrocarbon group having a hydroxyl group; and none of the threesubstituents contain an alkyl group having at its terminal either one of—CO₂M and —SO₃M in which M represents an atom or an atomic groupselected from hydrogen, an alkali metal, an alkaline earth metal, anammonium group and an organic amine group.

[0049] A twelfth aspect of the invention is to provide an ink jetrecording apparatus comprising at least a recording head including aliquid ejection surface having at least two nozzles for independentlyejecting at least two liquids, and a recording medium transfer sectionfor transferring a recording medium in one direction while the recordingmedium faces the liquid ejection surface and a shortest distance betweenthe recording medium and the liquid ejection surface is constantlymaintained, wherein:

[0050] during printing, an image is formed by ejecting the at least twoliquids onto a surface of the recording medium from the liquid ejectionsurface while moving the recording head in a direction substantiallyperpendicular to the transfer direction of the recording medium;

[0051] an ink set comprising at least two inks comprising at leastwater, a colorant and a water soluble organic solvent is used as the atleast two liquids; and

[0052] at least one ink in the ink set comprises at least one aminecompound represented by the following formula (2):

[0053] wherein the amine compound represented by the formula (2) is anyone of primary to tertiary amine compounds; at least one of threesubstituents represented by R₁′, R₂′ and R₃′ in the formula (2)comprises a hydrocarbon group having a hydroxyl group; and at least oneof the three substituents comprises a hydrocarbon group containing analkyl group having at its terminal either one of —CO₂M and —SO₃M inwhich M represents an atom or an atomic group selected from hydrogen, analkali metal, an alkaline earth metal, an ammonium group and an organicamine group.

[0054] A thirteenth aspect of the invention is to provide a colorlessink jet treatment liquid which is used together with an ink jet inkcomposition comprising at least water, a colorant and a water solubleorganic solvent, during printing, and comprises at least water and awater soluble organic solvent, wherein the ink jet treatment liquidcomprises at least one amine compound represented by the followingformula (1) in a range of 10 to 30% by mass:

[0055] wherein the amine compound represented by the formula (1) is anyone of primary to tertiary amine compounds; at least one of threesubstituents represented by R₁, R₂ and R₃ in the formula (1) comprises ahydrocarbon group having a hydroxyl group; and none of the threesubstituents contain an alkyl group having at its terminal either one of—CO₂M and —SO₃M in which M represents an atom or an atomic groupselected from hydrogen, an alkali metal, an alkaline earth metal, anammonium group and an organic amine group.

[0056] A fourteenth aspect of the invention is to provide a colorlessink jet treatment liquid which is used together with an ink jet inkcomposition comprising at least water, a colorant and a water solubleorganic solvent, during printing, and comprises at least water and awater soluble organic solvent, wherein the ink jet treatment liquidcomprises at least one amine compound represented by the followingformula (2):

[0057] wherein the amine compound represented by the formula (2) is anyone of primary to tertiary amine compounds; at least one of threesubstituents represented by R₁′, R₂′ and R₃′ in the formula (2)comprises a hydrocarbon group having a hydroxyl group; and at least oneof the three substituents comprises a hydrocarbon group containing analkyl group having at its terminal either one of —CO₂M and —SO₃M inwhich M represents an atom or an atomic group selected from hydrogen, analkali metal, an alkaline earth metal, an ammonium group and an organicamine group.

[0058] A fifteenth aspect of the invention is to provide an ink jetrecording method comprising forming an image by adhering an ink jet inkcomposition comprising at least water, a colorant and a water solubleorganic solvent, and a colorless ink jet treatment liquid comprising atleast water and a water soluble organic solvent, to approximately thesame region on a recording medium, wherein the ink jet treatment liquidcomprises at least one amine compound represented by the followingformula (1) in a range of 10 to 30% by mass:

[0059] wherein the amine compound represented by the formula (1) is anyone of primary to tertiary amine compounds; at least one of threesubstituents represented by R₁, R₂ and R₃ in the formula (1) comprises ahydrocarbon group having a hydroxyl group; and none of the threesubstituents contain an alkyl group having at its terminal either one of—CO₂M and —SO₃M in which M represents an atom or an atomic groupselected from hydrogen, an alkali metal, an alkaline earth metal, anammonium group and an organic amine group.

[0060] A sixteenth aspect of the invention is to provide an ink jetrecording method comprising forming an image by adhering an ink jet inkcomposition comprising at least water, a colorant and a water solubleorganic solvent, and a colorless ink jet treatment liquid comprising atleast water and a water soluble organic solvent, to approximately thesame region on a recording medium, wherein the ink jet treatment liquidcomprises at least one amine compound represented by the followingformula (2)

[0061] wherein the amine compound represented by the formula (2) is anyone of primary to tertiary amine compounds; at least one of threesubstituents represented by R₁′, R₂′ and R₃′ in the formula (2)comprises a hydrocarbon group having a hydroxyl group; and at least oneof the three substituents comprises a hydrocarbon group containing analkyl group having at its terminal either one of —CO₂M and —SO₃M inwhich M represents an atom or an atomic group selected from hydrogen, analkali metal, an alkaline earth metal, an ammonium group and an organicamine group.

[0062] A seventeenth aspect of the invention is to provide an ink jetrecording apparatus comprising at least a recording head including aliquid ejection surface comprising at least two nozzles forindependently ejecting at least two liquids, and a recording mediumtransfer section for transferring a recording medium in one directionwhile the recording medium faces the liquid ejection surface and ashortest distance between the recording medium and the liquid ejectionsurface is constantly maintained, wherein:

[0063] during printing, an image is formed by ejecting the at least twoliquids onto a surface of the recording medium from the liquid ejectionsurface while moving the recording head in a direction substantiallyperpendicular to the transfer direction of the recording medium;

[0064] an ink jet ink composition comprising at least water, a colorantand a water soluble organic solvent, and a colorless ink jet treatmentliquid comprising at least water and a water soluble organic solvent areused as the at least two liquids; and

[0065] the ink jet treatment liquid comprises at least one aminecompound represented by the following formula (1) in a range of 10 to30% by mass:

[0066] wherein the amine compound represented by the formula (1) is anyone of primary to tertiary amine compounds; at least one of threesubstituents represented by R₁, R₂ and R₃ in the formula (1) comprises ahydrocarbon group having a hydroxyl group; and none of the threesubstituents contain an alkyl group having at its terminal either one of—CO₂M and —SO₃M in which M represents an atom or an atomic groupselected from hydrogen, an alkali metal, an alkaline earth metal, anammonium group and an organic amine group.

[0067] An eighteenth aspect of the invention is to provide an ink jetrecording apparatus comprising at least a recording head including aliquid ejection surface comprising at least two nozzles forindependently ejecting at least two liquids, and a recording mediumtransfer section for transferring a recording medium in one directionwhile the recording medium faces the liquid ejection surface and ashortest distance between the recording medium and the liquid ejectionsurface is constantly maintained, wherein:

[0068] during printing, an image is formed by ejecting the at least twoliquids onto a surface of the recording medium from the liquid ejectionsurface while moving the recording head in a direction substantiallyperpendicular to the transfer direction of the recording medium;

[0069] an ink jet ink composition comprising at least water, a colorantand a water soluble organic solvent, and a colorless ink jet treatmentliquid comprising at least water and a water soluble organic solvent areused as the at least two liquids; and,

[0070] the ink jet treatment liquid comprises at least one aminecompound represented by the following formula (2),

[0071] wherein the amine compound represented by the formula (2) is anyone of primary to tertiary amine compounds; at least one of threesubstituents represented by R₁′, R₂′ and R₃′ in the formula (2)comprises a hydrocarbon group having a hydroxyl group; and at least oneof the three substituents comprises a hydrocarbon group containing analkyl group having at its terminal either one of —CO₂M and —SO₃M inwhich M represents an atom or an atomic group selected from hydrogen, analkali metal, an alkaline earth metal, an ammonium group and an organicamine group.

DETAILED DESCRIPTION OF THE INVENTION

[0072] The first major aspect and the second major aspect of the presentinvention will be sequentially described by dividing into an ink jet inkcomposition (may be referred to as an ink hereinafter), an ink set, anink jet treatment liquid, an ink jet recording method and an ink jetrecording apparatus. When the descriptions refer to both “first majoraspect” and “second major aspect” in the descriptions below, they may besimply referred to as “the invention”.

[0073] <Ink Jet Ink Composition, Ink Set and Ink Jet Treatment Liquid>

[0074] Ink Jet Ink Composition

[0075] The first major aspect and the second major aspect of the ink jetink compositions of the invention will be described separately at first,and matters common to both of them will be described thereafter.

[0076] The ink jet ink composition according to the first major aspectof the invention comprises at least water, a colorant and awater-soluble organic solvent, and comprises at least one amine compoundrepresented by the following formula (1) in a range of 10 to 30% bymass.

[0077] The amine compound represented by the formula (1) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁, R₂ and R₃ in the formula (1) comprises a hydrocarbongroup having a hydroxyl group; and none of the three substituentscontain an alkyl group having at its terminal either one of —CO₂M and—SO₃M in which M represents an atom or an atomic group selected fromhydrogen, an alkali metal, an alkaline earth metal, an ammonium groupand an organic amine group.

[0078] The ink jet ink composition of the first major aspect of theinvention can relieve or suppress curling of the recording medium andclogging of the nozzles.

[0079] Such effect has been found by the inventor, in the process ofinvestigations for preventing curling, in cases where ink contains theamine compound represented by the formula (1) in the range of 10 to 30%by mass.

[0080] While the mechanism of the curling preventing effect of the aminecompound represented by the formula (1), which is added to the ink ofthe first major aspect of the invention, is not entirely clear, theinventor of the invention presumes that the mechanism is as follows fromvarious results and discoveries obtained in the process ofinvestigations of the invention.

[0081] The amine compound represented by the formula (1) has a hydroxylgroup as a substituent of the nitrogen atom. When the ink containing thecompound is ejected from a recording head of the ink jet recordingapparatus and permeates into a recording medium, permeation isaccelerated by the effect of the nitrogen atom having a high affinitywith cellulose, and the amine compound represented by the formula (1)permeates deep into cellulose fibers.

[0082] After permeation of the amine compound represented by the formula(1) into the cellulose fibers, hydrogen bonds are formed between thehydroxyl group contained in the substituent linked to the nitrogen atomand the hydroxyl group of the cellulose. In addition, since the nitrogenatom in the amine molecule has an affinity with the hydrogen atom of thehydroxyl group of cellulose, physical bonds are presumed to be formedbetween the amine molecule and cellulose fibers.

[0083] The amine compound represented by the formula (1) is alignedamong the cellulose fibers by the two bonds described above, and astructure comprising cross-links among the cellulose fibers is formed.Since the amine compound represented by the formula (1) does not move inthe recording medium due to the bonds, whereby the cross-linkingstructure among the cellulose fibers can be maintained, the distanceamong the cellulose fibers can be prevented from shortening even whenwater is evaporated off from the recording medium. Consequently,occurrence of curling is suppressed.

[0084] The amine compound represented by the formula (1) is highlyhydrophilic and the compound also acts as a humectant. Accordingly,water that has permeated into the recording medium during the printingprocess can be maintained and rapid evaporation of water is suppressed.Since such a function is able to retard reconstruction of the hydrogenbonds and shortening of inter-cellulose distances caused by evaporationof water, it is possible for the amine molecule itself to become alignedalong the hydroxyl groups of the cellulose fiber.

[0085] In other words, the amine molecule itself is able to establish anenvironment for facilitating alignment among the cellulose fibers, dueto its humectant action. This humectant action enhances an effect forsuppressing shortening of the inter-cellulose distances to consequentlyresult in suppression of curling.

[0086] Moreover, since the amine compound represented by the formula (1)has an excellent humectant effect, evaporation of water in the inkfilled in the recording head through an ejection nozzle can also besuppressed. Accordingly, clogging is also unlikely to occur.

[0087] The content of the amine compound represented by the formula (1)is not particularly limited as long as it is in the range of 10 to 30%by mass. A range of 13 to 25% by mass is preferable, and a range of 15to 20% by mass is more preferable.

[0088] The curl-preventing effect cannot be obtained when the content ofthe amine compound represented by the formula (1) is less than 10% bymass, while clogging are generated when the content exceeds 30% by mass.

[0089] The amine compound used in the first major aspect of theinvention is not particularly limited so long as at least one of thethree substutitents represented by R₁, R₂ and R₃ in the formula (1)which are linked to the nitrogen atom comprises a hydrocarbon grouphaving a hydroxyl group, and none of the three substituents contain analkyl group having at its terminal either one of —CO₂M and —SO₃M (Mrepresents an atom or an atomic group selected from hydrogen, an alkalimetal, an alkaline earth metal, an ammonium group and an organic aminegroup).

[0090] The phrase “a hydrocarbon group having a hydroxyl group” as usedin the invention means known hydrocarbon groups having at least onehydroxyl group. The structure thereof is not particularly limited.

[0091] However, based on the considerations described above, the aminecompound used in the first major aspect of the invention preferablysatisfies the following conditions (1) to (3) from the viewpoint offacilitating the cross-linking structure between the cellulose fiber andthe amine compound:

[0092] (1) the hydroxyl group is positioned at the outermost side of theamine molecule;

[0093] (2) at least one hydroxyl group is contained in respectivesubstituents R₁, R₂ and R₃; and

[0094] (3) the substituents R₁, R₂ and R₃are not spatially bulky inorder to facilitate other molecules and polymers to approach thenitrogen atom positioned at the center of the amine molecule, and

[0095] the amine compound used in the first major aspect of theinvention preferably satisfies the following condition (4) from the viewpoint of maintaining an appropriate distance between the cross-linkingcellulose fibers that is neither too long nor too short

[0096] (4) at least the substituent containing the hydroxyl group of thesubstituents R₁, R₂ and R₃has an appropriate length.

[0097] It is preferable to satisfy the conditions of above (1) to (4).

[0098] However, it is practically preferable that the hydroxyl group iscontained in any two of the substituents R₁, R₂ and R₃ with respect tothe condition (2). This is because the amine compound containing atleast one hydroxyl group in respective substituents R₁, R₂ and R₃ has amolecular structure that is decomposed over time, and the product formedby decomposition becomes yellowish.

[0099] The hydroxyl group is preferably positioned at the terminal ofthe hydrocarbon group having the hydroxyl group for satisfying thecondition (1). A terminal functional group may interfere with thecross-linking structure between the hydroxyl group and cellulose fiberwhen the hydroxyl group is positioned at a position other than theterminal of the hydrocarbon group having the hydroxyl group.

[0100] The hydrocarbon group having the hydroxyl group preferablycomprises the hydrocarbon groups having the hydroxyalkyl group, morepreferably only the hydroxyalkyl group for satisfying the condition (3).

[0101] When the hydroxyl group in the hydrocarbon group is an aromaticgroup having the hydroxyl group, the substituent R (the substituent Rmeans at least any one of R₁, R₂ and R₃ hereinafter) is so spatiallybulky that other molecules and polymers may be blocked from approachingthe nitrogen atom positioned at the center of the amine molecule. Thehydroxyalkyl group is preferably a linear hydroxyalkyl group rather thana branched hydroxyalkyl group for reducing the spatial bulkiness.

[0102] The carbon number of the hydrocarbon group containing thehydroxyl group is preferably in the range of 1 to 5, more preferably inthe range of 1 to 3 and further preferably 1 or 2 for satisfying thecondition (4) when the hydrocarbon group having the hydroxyl groupcomprises a hydroxyalkyl group.

[0103] The cross-linking distance of the cross-linking made by aminemolecule between the cellulose fibers may be too short when the carbonnumber is zero, or when the hydroxyl group is directly linked to thenitrogen atom. The cross-linking distance may be too long when thecarbon number exceeds 5.

[0104] When the hydrocarbon group having the hydroxyl group has astructure other than the linear hydroxyalkyl group, or when hydrocarbongroup having the hydroxyl group contains the linear hydroxyalkyl group(for example when the linear hydroxyalkyl group is linked to the benzenering), the length of the hydrocarbon group containing the hydroxyl grouphaving the structure as described above preferably corresponds to thelength of the hydroxyalkyl group having a carbon number in the range of1 to 5.

[0105] Examples of the amine molecule available having the hydrocarbongroup containing the hydroxyl group as described above includebis(hydroxyalkyl)monoalkylamines such as N-ethyl diethanolamine,tris(hydroxyalkyl)amines such as tris(2-hydroxyethyl)amine,1-[N,N-bis(2-hydroxyethyl)amino]-2-propanol and2,2-bis(hydroxymethyl)-2,2,′,2″-nitriloethanol, and monohydroxyalkylamines such as 2-aminoethanol.

[0106] The ink jet ink composition according to the second major aspectof the invention will be described below. The ink jet ink composition ofthe second major aspect of the invention comprises at least water, acolorant and water-soluble organic solvent, and comprises at least oneamine compound represented by the formula 2.

[0107] The amine compound represented by the formula (2) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁′, R₂′ and R₃′ in the formula (2) comprises ahydrocarbon group having a hydroxyl group; and at least one of the threesubstituents comprises a hydrocarbon group containing an alkyl grouphaving at its terminal either one of —CO₂M and —SO₃M in which Mrepresents an atom or an atomic group selected from hydrogen, an alkalimetal, an alkaline earth metal, an ammonium group and an organic aminegroup.

[0108] Accordingly, when the recording medium is printed on using theink jet ink composition according to the second major aspect of theinvention, curling of the recording medium and clogging of the nozzleare relieved or suppressed while the image density is further improved.

[0109] The amine compound represented by the formula (2) and used forthe ink according to the second major aspect of the invention canrelieve or suppress curling of the recording medium and clogging of thenozzle similarly to the amine used for the ink according to the firstmajor aspect of the invention.

[0110] It is thought that at least one of the three substituents in theamine compound used for the ink according to the second major aspect ofthe invention comprises a hydrocarbon group having a hydroxyl group asthe amine compound used for the ink according to the first major aspectof the invention does. It is preferable that the number of thehydrocarbon group having the hydroxyl group contained in the aminemolecule, and the structure of the hydrocarbon group having the hydroxylgroup contained in the amine molecule in the second major aspect are thesame as those of the amine compound used for the ink according to thefirst major aspect of the invention.

[0111] It was confirmed from the results of investigations by theinventor of the invention that curling of the recording medium andclogging of the nozzle are relieved or suppressed while the imagedensity is further improved, when the amine compound used for the inkaccording to the second major aspect of the invention is added to theink.

[0112] This effect of further improving the image density may beascribed to the fact that, different from the amine compound used in thefirst major aspect of the invention, at least one of three substituentsrepresented by R₁′, R₂′ and R₃′ of the amine compound used for the inkaccording to the second major aspect of the invention comprises ahydrocarbon group containing an alkyl group having at its terminaleither one of —CO₂M and —SO₃M in which M represents an atom or an atomicgroup selected from hydrogen, an alkali metal, an alkaline earth metal,an ammonium group and an organic amine group (may be referred to as“alkylcarboxylic acid derivative groups” or “alkylsulfonic acidderivative groups” hereinafter). More specifically, the reason isthought that the —CO₂M and —SO₃M groups contained in the alkylcarboxylicacid derivative groups and alkylsulfonic acid derivative groups have afunction for accelerating coagulation of pigments when the derivativescontact the recording medium.

[0113] Such effect of improving the image density may be caused by thefollowing phenomenon.

[0114] Inside ink droplets that result when ink bombards the recordingmedium after being ejected from the recording head as fine dropletsduring printing, the amine compound containing the alkylcarboxylic acidderivative and/or alkylsulfonic acid derivative as the substituent R′(hereinafter “substituent R′” means at least any one of R₁′, R₂′ andR₃′)is aligned at the surface of the droplets and at the interfacebetween ink droplets and the recording medium. Therefore, aconcentration gradient of the amine molecule is formed within the inkdroplets. The —CO₂M or —SO₃M group contained in the amine moleculeinhibits the colorant in the ink from stably dispersing at the portionswhere the concentration of the amine molecule is high in the inkdroplets, and accelerates coagulation of the a colorant. Accordingly dueto this phenomenon, the colorant becomes more likely to remain on thesurface of the recording medium to improve the image density.

[0115] The alkylcarboxylic acid derivative group or alkylsulfonic acidderivative group contained in the amine molecule used in the inkaccording to the second major aspect of the invention may contain thehydroxyl group. However, since the hydroxyl group cannot be positionedat the terminal in this case, the amine molecule preferably contains nohydroxyl group.

[0116] Since the number of the hydrocarbon group containing the hydroxylgroup contained in the amine molecule used for the ink according to thesecond major aspect of the invention is most preferably 2 as describedabove, the number of the carboxylic acid derivative group oralkylsulfonic acid derivative group is preferably 1.

[0117] Specific examples of the amine molecule used for the inkaccording to the second major aspect of the invention described aboveinclude N,N-bis(hydroxyethyl)glycine, N,N-bis(hydroxyethyl)glycinesodium salt, N,N-bis(hydroxyethyl)glycine ammonium salt,N,N-bis(hydroxymethyl)glycine, N,N-bis(hydroxymethyl)glycine sodiumsalt, N,N-bis(hydroxymethyl)glycine ammonium salt,N,N-bis(hydroxyethyl)-2-aminoethane sulfonic acid, sodium sodiumN,N-bis(hydroxyethyl)-2-aminoethane sulfonate, ammoniumN,N-bis(hydroxyethyl)-2-aminoethane sulfonate,N,N-bis(hydroxymethyl)-2-aminoethane sulfonic acid, sodiumN,N-bis(hydroxymethyl)-2-aminoethane sulfonate, ammoniumN,N-bis(hydroxymethyl)-2-aminoethane sulfonate, and torisine sodium salt(N-[tris(hydroxymethyl)methyl]glycine sodium salt.).

[0118] The amine molecules more preferable among them includeN,N-bis(hydroxyalkyl)glycine derivatives andN,N-bis(hydroxyalkyl)-2-aminoethane sulfonic acid derivatives, and it isparticularly preferable that the hydroxyalkyl portion of these aminederivative molecules is hydroxyethyl.

[0119] While the content of amine compound represented by the formula(2) is not particularly limited in the ink according to the second majoraspect of the invention, it is preferably in the range of 5 to 30% bymass, more preferably 13 to 25% by mass, and further preferably 15 to20% by mass.

[0120] The curl-preventing effect cannot be obtained when the content ofthe amine compound represented by the formula (2) is less than 3% bymass. On the other hand, clogging may occur when the content exceeds 30%by mass.

[0121] The contents common in both inks in the first and second majoraspects of the invention (both inks in both the first and second majoraspects of the invention are named as the ink according to the inventionhereinafter) will be described in detail below.

[0122] The amine compound used for the ink of the invention ispreferably a solid in a pure state at room temperature. Consequently,the melting point or decomposition point of the amine compound ispreferably 50° C. or more, more preferably 100° C. or more, andparticularly 180° C. or more.

[0123] The phrase “the melting point or decomposition point of the aminecompound” refers to a lower temperature of the melting point anddecomposition point of the amine compound when the compound has bothpoints.

[0124] When the amine compound has a melting point or decompositionpoint at 50° C. or more, the amine compound represented by the formula(1) or (2) is a solid under a general environment of use. The aminecompound is remained in the recording medium after the ink has beendried, and is fixed among the cellulose fibers while the compound isaligned. Accordingly, the amine compound works as a paperstrength-enhancing agent. Consequently, the amine compound is able toexhibit stronger curl-preventing effect as compared with an aminecompound having a melting point or decomposition point less than 50° C.Since the amine compound functions as a paper strength-enhancing agentwhen its melting point or decomposition point is 50° C. or more, curl issuppressed even when letters and pictures are printed over a printedmatter that has been printed with an ink containing such amine compound.Examples of the amine compound having a melting point or decompositionpoint of 50° C. or more include the amine compounds that have beenexemplified as the amine compound used for the ink in the second majoraspect of the invention.

[0125] The ink of the invention preferably has a surface tension of 40mN/m or less, more preferably 25 mN/m to 35 mN/m.

[0126] Although conventional inks having the surface tension in therange described above were excellent in permeability and was used as arapidly drying ink, such ink has a contradictory property that curl wasliable to occur due to permeation of the ink into the recording medium.However, the ink of the invention containing the amine compoundrepresented by the formula (1) or (2) is able to suppress curling evenwhen the ink permeates deep into the recording medium. Consequently, theink of the invention can retain the rapidly drying property as well asthe curl-suppressing property when the surface tension of the ink of theinvention is within the range as described above.

[0127] The ink of the invention may contain both the amine compoundrepresented by the formula (1) and the amine compound represented by theformula (2). When the proportion of the former amine compound isrelatively large or the proportions of both amine compounds areapproximately the same, the content of all the amine compounds containedin the ink should be within the range of 10 to 30% by mass as in the inkaccording to the first major aspect of the invention.

[0128] On the other hand, when the proportion of the latter aminecompound is relatively large, the content of all the amine compoundscontained in the ink is preferably within the range of 5 to 35% by mass,although the content is not particularly limited.

[0129] Ink Set

[0130] The ink set of the invention will be described below. At leasttwo inks such as a combination of cyan, magenta, yellow and black arefrequently used as a set for printing using the ink. Each inkconstituting the ink set contains at least water, a colorant and a watersoluble organic solvent.

[0131] The invention provides, in the first major aspect, an ink setcomprising at least one ink containing the amine compound represented bythe formula (1) in a range of 10 to 30% by mass.

[0132] Curling of the recording medium and clogging of the nozzle arerelieved or suppressed when the recording medium is printed using suchink set. The ink containing the amine compound in the ink set isbasically the same as the ink in the first major aspect of theinvention, except that the ink is used as a set with other inks.

[0133] While all the color inks in the ink set may contain the aminecompound represented by the formula (1), it is not always necessary. Inthis case, it is more preferable that the ink that is easy to be used ina wide area on the recording medium contains the amine compoundrepresented by the formula (1).

[0134] For example, color inks and pale color inks such as light colorinks having a lower color density than color ink are mainly used at theportions of the recording medium that may largely affect curling such asgraphs and photographs. On the other hand, since deep color inks such asa black ink are mainly used for printing letters, the ink has littleinfluence on curling.

[0135] When the ink set comprises a combination of at least one palecolor ink and at least one deep color ink, the amine compoundrepresented by the formula (1) is preferably added in at least one palecolor ink. The amine compound represented by the formula (1) may beadded or not added into the deep color ink that slightly influences oncurling.

[0136] In the second major aspect, the invention provides an ink setcomprising at lest one ink containing the amine compound represented bythe formula (2).

[0137] Curling of the recording medium and clogging of the nozzle arerelieved or suppressed while the image density is further improved byprinting an image on the recording medium using such ink set. The inkcontaining the amine compound in the ink set is basically the same asthe ink in the second major aspect of the invention, except that the inkis used as a set with other inks.

[0138] While all the color inks in the ink set may contain the aminecompound represented by the formula (2), it is not always necessary. Inthis case, it is more preferable that the ink that is easy to be used ina wide area on the recording medium contains the amine compoundrepresented by the formula (2).

[0139] The ink of the invention may contain both the amine compoundrepresented by the formula (1) and the amine compound represented by theformula (2). When the proportion of the former amine compound isrelatively large or the proportions of both amine compounds areapproximately the same, the content of all the amine compounds containedin the ink should be within the range of 10 to 30% by mass as in the inkaccording to the first major aspect of the invention.

[0140] On the other hand, when the proportion of the latter aminecompound is relatively large, the content of all the amine compoundscontained in the ink is preferably within the range of 5 to 30% by massas in the ink set according to the second major aspect of the invention,although the content is not particularly limited.

[0141] Ink Jet Treatment Liquid

[0142] A colorless ink jet treatment liquid (a treatment liquidcontaining at least water and a water soluble organic solvent) may beused together with inks containing a colorant (inks containing at leastwater, a colorant and a water soluble organic solvent) for printing animage using the inks. Such treatment liquid is applied on the area ofthe recording medium on which the inks are applied before or after theinks are applied on the recording medium.

[0143] The treatment liquid according to the first major aspect of theinvention comprises the amine compound represented by the formula (1) ina range of 10 to 30% by mass.

[0144] Curling of the recording medium and clogging of the nozzle arerelieved or suppressed by printing an image on the recording mediumusing such ink set. Preferable structures and examples of the aminecompound represented by the formula (1) are the same as described abovefrom this point of view. The treatment liquid according to the firstmajor aspect of the invention is particularly effective when used incombination with the inks having no curl-suppressing effect.

[0145] The treatment liquid according to the second major aspect of theinvention contains the amine compound represented by the formula (2).

[0146] Curling of the recording medium and clogging of the nozzle arerelieved or suppressed while the image density is further improved byprinting an image on the recording medium using the treatment liquidtogether with the inks. Preferable structures and examples of the aminecompound represented by the formula (2) are the same as described abovefrom this pint of view. The treatment liquid according to the secondmajor aspect of the invention is particularly effective when used incombination with the inks having no curl-suppressing effect.

[0147] The treatment liquid may contain both the amine compoundrepresented by the formula (1) and the amine compound represented by theformula (2). When the proportion of the former amine compound isrelatively large or the proportions of both amine compounds areapproximately the same, the content of all the amine compounds containedin the ink should be within the range of 10 to 30% by mass as in thetreatment liquid according to the first major aspect of the invention.

[0148] On the other hand, when the proportion of the latter aminecompound is relatively large, the content of all the amine compoundscontained in the treatment liquid is preferably within the range of 5 to30% by mass as in the treatment liquid according to the second majoraspect of the invention, although the content is not particularlylimited.

[0149] Colorant, water-soluble organic solvent and other additives

[0150] The colorant contained in each color constituting the ink or inkset, water-soluble organic solvent and other additives in the presentinvention, and the water-soluble organic solvent and other additivescontained in the treatment liquid will be described below.

[0151] The colorant used in the invention may be a dye or pigment.Examples of the dye available include a direct dye, acidic dye, edibledye, basic dye, reactive dye, dispersion dye, vat dye, soluble vat dye,reactive dispersion dye and oil soluble dye.

[0152] Examples of the dye include C.I. direct black-2, -4, -9, -11,-17, -19, -22, -32, -80, -151, -154, -168, -171, -194 and -195; C.I.direct blue-1, -2, -6, -8, -22, -34, -70, -71, -76, -78, -86, -112,-142, -165, -199, -200, -201, -202, -203, -207, -218, -236, -287 and-307; C.I. direct red -1, -2, -4, -8, -9, -11, -13, -15, -20, -28, -31,-33, -37, -39, -51, -59, -62, -63, -73, -75, -80, -81, -83, -87, -90,-94, -95, -99, -101, -110, -189 and -227; C.I direct violet-2, -5, -9,-12, -18, -25, -37, -43, -66, -72, -76, -84, -92 and-107; C.I, directyellow-1, -2, -4, -8, -11, -12, -26, -27, -28, -33, -34, -41, -44, -48,-58, -86, -87, -88, -132, -135, -142, -144 and -173; C.I. food black-1and -2; C.I. acid black-1, -2, -7, -16, -24, -26, -28, -31, -48, -52,-63, -107, -112, -118, -119, -121, -156, -172, -194 and -208; C.I. acidblue-1, -7, -9, -15, -22, -23, -27, -29, -40, -43, -55, -59, -62, -78,-80, -81, -83, -90, -102, -104, -111, -185, -249 and -254; C.I. acidred-1, -4, -8, -13, -14, -15, -18, -21, -26, -35, -37, -52, -110, -144,-180, -249 and -257; C.I. acid yellow-1, -3, -4, -7, -11, -12, -13, -14,-18, -19, -23, -25, -34, -38, -41, -42, -44, -53, -55, -61, -71, -76,-78, -79 and -122.

[0153] These dyes maybe used alone, or as a mixture of a plurality ofthem. The content of these dyes in the ink of the invention ispreferably in the range of 0.1 to 10% by mass, more preferably in therange of 1 to 8% by mass, relative to the total mass of the ink.

[0154] Either organic pigments or inorganic pigments may be used as thepigments in the colorant of the invention.

[0155] Examples of the black pigment include carbon black pigments suchas furnace black, lamp black, acetylene black and channel black such asRaven 7000, Raven 5750, Raven 5250, Raven 5000 ULTRA II, Raven 3500,Raven 2000, Raven 1500, Raven 1250, Raven 1200, Raven 1190 ULTRA II,Raven 1170, Raven 1255, Raven 1080 and Raven 1060 (manufactured byColumbian Chemicals Company); Regal 1400R, Regal 1330R, Regal 1660R,Mogul L. Black Pearls L, Monarch 700, Monarch 800, Monarch 1000, Monarch1100, Monarch 880, Monarch 900, Monarch 1300 and Monarch 1400(manufactured by Cabot Corporation); Color Black FW1, Color Black FW2,Color Black FW2V, Color Black 18, Color Black FW200, Color Black S150,Color Black S160, Color Black S170, Printex 35, Printex U, Printex V,Printex 140U, Printex 140V, Special Black 6, Special Black 5, SpecialBlack 4A and Special Black 4 (manufactured by Degssa Co.); and No. 25,No. 33, No. 40, No. 47. No. 52. No. 900. No. 2300, MCF-88, MA 600, MA 7,MA 8 and MA 100 (manufactured by Mitsubishi Chemical Co., Ltd.).However, the black pigments are not limited thereto.

[0156] Examples of the cyan pigment include C.I. Pigment Blue-1, C.I.,C.I. Pigment Blue-2, C.I. Pigment Blue-3, C.I. Pigment Blue-15, C.I.Pigment Blue-15:1, C.I. Pigment Blue-15:3, C.I. Pigment Blue-15:4, C.I.Pigment Blue-16, C.I. Pigment Blue-22 and C.I. Pigment Blue-60. However,the cyan pigments are not limited thereto.

[0157] Examples of magenta pigment include C.I. Pigment Red-5, C.I.Pigment red-7, C.I. Pigment red-12, C.I. Pigment red-48, C.I. PigmentRed-48: I.C.I. Pigment Red-57, C.I. Pigment Red-112, C.I. PigmentRed-122, C.I. Pigment Red-123, C.I. Pigment Red-146, C.I. PigmentRed-168, C.I. Pigment Red-184 and C.I. Pigment Red-202. However themagenta pigments are not limited thereto.

[0158] Examples of yellow pigment include C.I. Pigment Yellow-1, C.I.Pigment Yellow-2, C.I. Pigment Yellow-3, C.I. Pigment Yellow-12, C.I.Pigment yellow-13, C.I. Pigment yellow-14, C.I. Pigment Yellow-16, C.I.Pigment Yellow-17, C.I. Pigment Yellow-73, C.I. Pigment yellow-74, C.I.Pigment yellow-75, C.I. Pigment Yellow-83, C.I. Pigment Yellow-93, C.I.Pigment Yellow-95, C.I. Pigment yellow-97, C.I. Pigment yellow-98, C.I.Pigment Yellow-114, C.I. Pigment Yellow-128, C.I. Pigment Yellow-129,C.I. Pigment Yellow-138, C.I. Pigment Yellow-151 and C.I. PigmentYellow-154. However, the yellow pigments are not limited thereto.

[0159] These pigments may be used alone, or as a mixture of a pluralityof them. The pigment used in the ink of the invention is used in therange of 0.5 to 20% by mass, preferably 2 to 10% by mass, relative tothe total weight of the ink.

[0160] A pigment dispersant is preferably used together when the pigmentis used as the colorant. Examples of the pigment dispersant availableinclude polymer dispersants, anionic surfactants, cationic surfactants,amphoteric surfactants and nonionic surfactants. With respect to thepolymer dispersants, polymer having hydrophobic structure part andhydrophilic structure part may effectively be used. Condensationpolymers and addition polymers may be used as polymers having ahydrophobic structure part and hydrophilic structure part. Examples ofthe condensation polymer include known polyester dispersants.

[0161] Examples of the addition polymer include addition polymers ofmonomers having α, β-ethylenic unsaturation bonds. A desired polymerdispersant is obtained by a copolymerization of an appropriatecombination of a hydrophilic monomers having α, β-ethylenic unsaturationbonds and a hydrophobic monomer having α, β-ethylenic unsaturationbonds. A homopolymer of hydrophilic monomers having α, β-ethylenicunsaturation bonds may be also used.

[0162] Examples of the hydrophilic monomer having α, β-ethylenicunsaturation bonds include monomers having carboxyl, sulfonic acid,hydroxyl or phosphoric acid groups, for example acrylic acid,methacrylic acid, crotonic acid, itaconic acid, itaconic acid monoester,maleic acid, maleic acid monoester, fumaric acid, fumaric acidmonoester, vinylsulfonic acid, styrenesulfonic acid, sulfonatedvinylnaphthalene, vinyl alcohol, acrylamide, methacryloxyethylphosphate, bismethacryloxyethyl phosphate, methacryloxyethylphenyl acidphosphate, ethyleneglycol dimethacrylate and diethyleneglycoldimethacrylate.

[0163] Examples of the hydrophobic monomer having α, β-unsaturated bondsinclude styrene derivatives such as styrene, α-methylstyrene andvinyltoluene; vinylcyclohexane, vinylnaphthalene, vinylnaphthalenederivatives, alkyl acrylate, alkyl methacrylate, phenyl methacrylate,cycloalkyl methacrylate, alkyl crotonate, dialkyl itaconate and dialkylmaleate.

[0164] Examples of the preferable copolymer includestyrene-stylenesulfonic acid copolymer, styrene-maleic acid copolymer,styrene-methacrylic acid copolymer, styrene-acrylic acid copolymer,vinylnaphthalene-maleic acid copolymer, vinylnaphthalene-methacrylicacid copolymer, vinylnaphthalene-acrylic acid copolymer, alkylacrylate-acrylic acid copolymer, alkyl methacrylate-methacrylic acidcopolymer, styrene-alkyl acrylate-methacrylic acid copolymer,styrene-alkyl acrylate-acrylic acid copolymer, styrene-phenylmethacrylate-methacrylic acid copolymer, and styrene-cyclohexylmethacrylate-methacrylic acid copolymer. Monomers having polyoxyethylenegroups or hydroxyl groups may be appropriately copolymerized with thesecopolymers.

[0165] These pigment dispersants may be used alone, or as a combinationof at least two of them. While the amount of addition of the pigmentdispersant cannot be necessarily defined, the combined proportion isusually 0.1 to 100% by mass, preferably 1 to 70% by mass, and morepreferably 3 to 50% by mass relative to the amount of the pigment.

[0166] Self-dispersing pigment may be used as the pigment of theinvention. Specific examples of suchpigment are Cab-o-jet 200, Cab-o-jet300, IJX-253, IJX-266, IJX-273, IJX-444 and IJX-55 manufactured by CabotCorporation, and Microjet Black CW-1 and CW-2 manufactured by OrientChemical Industries, Ltd. However, the pigment is not limited thereto.

[0167] So-called capsulated pigments prepared by coating pigmentparticles with a polymer may be also used as the pigment in theinvention.

[0168] A cationic surfactant, nonionic surfactant and/or anionicsurfactant may be added to the ink and treatment liquid in the inventionin order to control the surface tension an wettability of the ink andtreatment liquid. These surfactants may be used alone, or as a mixtureof a plurality of them.

[0169] The amount of addition of the surfactant to the ink is preferably5% by mass or less, more preferably in the range of 0.01 to 3% by weightrelative to the total amount of the ink.

[0170] Examples of the water-soluble organic solvent used in theinvention include polyfunctional alcohols such as ethyleneglycol,diethyleneglycol, propyleneglycol, butyleneglycol, triethyleneglycol,1,5-pentadiol, 1,2,6-hexanetriol and glycerin; polyfunctional alcoholderivatives such as ethyleneglycol monomethylether, ethyleneglycolmonoethylether, ethyleneglycol monobutylether, diethyleneglycolmonomethylether, diethyleneglycol monoethylether, diethyleneglycolmonobutylether, diethyleneglycol monohexylether, triethyleneglycolmonobutylether, propyleneglycol monobutylether and dipropyleneglycolmonobutylether; nitrogen-containing solvents such as N-methylpyrrolidoneand cyclohexyl pyrrolidone; alcohols such as ethanol, isopropyl alcohol,butyl alcohol and benzyl alcohol: sulfur-containing solvents such asthiodiethanol, thiodiglycerol, sulfolane and dimethylsulfoxide; andpropylene carbonate and ethylene carbonate.

[0171] These water-soluble solvents may be used alone, or as a mixtureof at least two of them.

[0172] While the content of the water-soluble organic solvent in the inkis not particularly limited, it is preferably 1 to 60% by mass, morepreferably 5 to 40% by mass, relative to that total weight of the ink.

[0173] Other components such as polyethylene imine, polyvinylpyrrolidone, polyethyleneglycol, cellulose derivatives such as ethylcellulose and carboxymethyl cellulose, and other water soluble polymers;polymer emulsions such as acrylic polymer emulsion and polyurethaneemulsion; and cyclodextrin, large ring amine, dendrimer, crown ether,urea and its derivatives, and acetamide may be added to the ink andtreatment liquid of the invention in addition to the componentsdescribed above.

[0174] Alkali metal compounds such as potassium hydroxide, sodiumhydroxide and lithium hydroxide; alkaline earth metal compounds such ascalcium hydroxide; acids such as sulfuric acid, hydrochloric acid andnitric acid; and slats of strong acids and weak alkali such as ammoniumsulfate may be used in the ink and treatment liquid of the invention foradjusting conductivity and pH.

[0175] Other additives such as a pH buffer agent, antioxidant,fungicide, viscosity control agent, conductive agent, UV absorber andcheating agent as well as water-soluble dyes, dispersion dyes and oilsoluble dyes maybe added, if necessary.

[0176] <Ink Jet Recording Method>

[0177] In the first major aspect, the invention provides an ink jetrecording method comprising forming an image by adhering an ink to arecording medium by using the ink of the first major aspect of theinvention or the ink set of the first major aspect of the invention, orforming an image by adhering a treatment liquid and an ink to arecording medium by using the treatment liquid of the first major aspectof the invention and an ink together.

[0178] Accordingly, curling of the recording medium and clogging of thenozzle are relieved or by printing the images on the recording medium bytaking advantage of the ink jet recording method according to the firstmajor aspect of the invention.

[0179] The invention also provides, in the second major aspect, an inkjet recording method comprising forming an image by adhering an ink to arecording medium by using the ink of the second major aspect of theinvention or the ink set of the second major aspect of the invention, orforming an image by adhering a treatment liquid and an ink to arecording medium by using the treatment liquid of the second majoraspect of the invention and an ink together.

[0180] Accordingly, curling of the recording medium and clogging of thenozzle are relieved or suppressed while the image density is improved byprinting the images on the recording medium by taking advantage of theink jet recording method according to the second major aspect of theinvention.

[0181] In more detail, the image is formed on the recording medium byejecting ink droplets, or ink droplets and treatment liquid droplets,through an orifice depending on recording signals in the ink jetrecording method of the invention.

[0182] Examples of the recording method used in ink jet recordinginclude a so-called static control method in which the ink, or the inkand treatment liquid are ejected by taking advantage of an staticattraction, a so-called piezo-method in which the ink, or the ink andtreatment liquid are ejected by taking advantage of a oscillationpressure of a piezoelectric element, and a so-called thermal inkjetmethod in which droplets of the ink and treatment liquid are formed bytaking advantage of a pressure that is generated from air bubbleformation and growth with heating the ink and treatment liquid. Thethermal inkjet method and piezo-method are particularly preferable amongthem since full-color images may be provided using a small size andinexpensive ink jet recording apparatus.

[0183] <Ink Jet Recording Apparatus>

[0184] In the first major aspect, the invention provides an ink jetrecording apparatus comprising at least a recording head including aliquid ejection surface having a nozzle for ejecting a liquid, and arecording medium transfer section for transferring a recording medium inone direction while the recording medium faces the liquid ejectionsurface and a shortest distance between the recording medium and liquidejection surface is constantly maintained. During printing, an image isformed by ejecting the liquid onto a surface of the recording mediumfrom the liquid ejection surface while moving the recording head in adirection substantially perpendicular to the transfer direction of therecording medium. The ink jet recording apparatus uses, as the liquid,the ink according to the first major aspect of the invention, the inkset according to the first major aspect of the invention, or thetreatment liquid according to the first major aspect of the inventionand an ink (an ink set) together.

[0185] Accordingly, curling of the recording medium and clogging of thenozzle is relieved or suppressed by printing the images on the recordingmedium using the ink jet recording apparatus according to the firstmajor aspect of the invention.

[0186] In the second major aspect, the invention provides an ink jetrecording apparatus comprising at least a recording head including aliquid ejection surface having a nozzle for ejecting a liquid, and arecording medium transfer section for transferring a recording medium inone direction while the recording medium faces the liquid ejectionsurface and a shortest distance between the recording medium and theliquid ejection surface is constantly maintained. During printing, animage is formed by ejecting the liquid onto a surface of the recordingmedium from the liquid ejection surface while moving the recording headin a direction substantially perpendicular to the transfer direction ofthe recording medium. The ink jet recording apparatus uses, as theliquid, the ink according to the second major aspect of the invention,the ink set according to the second major aspect of the invention, orthe treatment liquid according to the second major aspect of theinvention and an ink (an ink set) together.

[0187] Accordingly, curling of the recording medium and clogging of thenozzle is relieved or suppressed while the image density is furtherimproved by printing the images on the recording medium using the inkjet recording apparatus according to the second major aspect of theinvention.

[0188] Known recording methods such as the piezo-method and thermalinkjet method as used in the ink jet recording method of the inventionmay be used as the recording method used in the ink jet recordingapparatus of the invention. Examples of known ink jet recordingapparatus are described in JP-A No. 2002-275401, which is incorporatedby reference herein in its entirety. A liquid is ejected from thenozzle, and the recording head is transferred in substantiallyperpendicular direction to the transfer direction of the recordingmedium during the printing process in accordance with image signals sentto the recording head. The ink jet printer of the invention may furthercomprise known constructions, members and functions other than thosedescribed above, if necessary.

[0189] When at least two liquids such as the ink set of the invention ora combination of a ink (or an ink set) and the treatment liquid of theinvention are used as the liquids for printing, the recording head usedhas an ejection surface comprising at least two nozzles forindependently ejecting the at least two liquids.

[0190] When an ink (or an ink set) is used in combination with thetreatment liquid of the invention, the treatment liquid is applied onthe region of the recording medium on which the ink is applied. Theorder of applying the ink and treatment liquid is not particularlylimited, and the treatment liquid may be applied after applying the inkor vice versa.

[0191] The shortest distance between the liquid ejection surface and theplane surface of the recording medium is preferably in the range of 1.0to 2.0 mm, more preferably in the range of 1.2 to 1.7 mm, in the ink jetrecording apparatus of the invention.

[0192] The air stream generated by scanning of the recording head and/ortransfer of the recording medium may disturb the ejection direction ofthe ink and treatment liquid when the shortest distance between theliquid ejection surface and the plane surface of the recording medium isless than 1.0 mm. Consequently, the ink and treatment liquid is ejectedin a wrong direction to cause irregularity and moire of the image.

[0193] When the shortest distance between the liquid ejection surfaceand the plane surface of the recording medium exceeds 2.0 mm, on theother hand, the bombardment position of the droplet on the recordingmedium may be hardly controlled, since the distance for allowing the inkand treatment liquid ejected from the liquid ejection surface to arriveat the recording medium is elongated. Consequently, fine images may behardly formed.

[0194] The shortest distance between the liquid ejection surface and theplane surface of the recording medium is adjusted to be within the rangeof 1.0 to 2.0 mm in the conventional ink jet recording apparatus inorder to avoid the problems described above. However, the recordingmedium is swelled and undulated due to curling of the recording mediumimmediately after printing when the largest length of the recordinghead, which is mounted on the ink jet recording apparatus, in thetransfer direction of the recording medium (hereinafter, occasionallyabbreviated as “recording head length”) is 1 inch (2.54 cm) or more.Consequently, the conventional ink jet recording apparatus may suffer aproblem in that the recording medium contacts the recording head.

[0195] The recording medium is transferred to a position that enablesthe recording medium to avoid from contacting the head before theprinted portion of the recording medium is swelled when the head lengthis less than 1 inch. Accordingly, the recording head hardly contacts therecording medium. However, when the length of the recording head is 1inch or more, it takes a long time before the recording medium istransferred to a position where the recorded portions swelled byadhesion of the ink and treatment liquid does not contact the printinghead. Some measures were necessary for reducing the possibility ofcontact between the printing head and the recording medium.

[0196] On the other hand, the ink of the invention or the ink set of theinvention is used as the liquid used for printing in the ink jetrecording apparatus of the invention, or the treatment liquid of theinvention and an ink (an ink set) are used together as the liquids usedfor printing in the recording apparatus of the invention. Consequently,undulating of the recording medium immediately after printing can besuppressed.

[0197] In other words, the troubles of contact between the recordingmedium and recording head can be solved in the ink jet recordingapparatus of the invention, even when a recording head with a length of1 inch or more, which has often caused troubles, is mounted.

[0198] The length of the recording head is preferably 7.5 cm or less,since the recording medium may contact the recording head when thelength is 7.5 cm or more.

EXAMPLES

[0199] While the present invention is described in more detail withreference to examples, the invention is by no means limited to theseexamples.

Example 1

[0200] After mixing the components below, an ink is prepared byfiltering with a membrane filter with a pore size of 5 μm.

[0201] Dispersed solution of self-dispersing pigment (CAB-O-JET 300,manufactured by Cabot Corporation): 3% by mass

[0202] Diethyleneglycol: 1.5% by mass

[0203] N,N-bis(hydroxyethyl)glycine: 15% by mass

[0204] Sodium hydroxide: 1.5% by mass

[0205] Olfin E10110 (manufactured by Nissin Chemical Industry Co.,Ltd.): 0.2% by mass

[0206] Pure water: the balance

Example 2

[0207] After mixing the components below, an ink is prepared byfiltering with a membrane filter with a pore size of 5 μm.

[0208] Dispersed solution of self-dispersing pigment (CAB-O-JET 200,manufactured by Cabot Corporation): 3% by mass

[0209] Glycerin: 10% by mass

[0210] Sulfolane: 10% by mass

[0211] N,N-bis(hydroxyethyl)-2-aminoethane sulfonic acid: 15% by mass

[0212] Sodium hydroxide: 1.2% by mass

[0213] Olfin E10110 (manufactured by Nissin Chemical Industry Co.,Ltd.): 0.2% by mass

[0214] Pure water: the balance

Example 3

[0215] After mixing the components below, an ink is prepared byfiltering with a membrane filter with a pore size of 5 μm.

[0216] Dispersed solution of self-dispersing pigment (CAB-O-JET 300,manufactured by Cabot Corporation): 3% by mass

[0217] diethyleneglycol: 15% by mass

[0218] N,N-bis(hydroxyethyl)glycine: 15% by mass

[0219] Sodium hydroxide: 1.5% by mass

[0220] E215 (manufactured by Nippon Oil & Fats Co., Ltd.): 0.5% by mass

[0221] Pure water: the balance

Example 4

[0222] After mixing the components below, an ink is prepared byfiltering with a membrane filter with a pore size of 5 μm.

[0223] Dispersed solution of self-dispersing pigment (CAB-O-JET 253,manufactured by Cabot Corporation): 3% by mass

[0224] propyleneglycol: 10% by mass

[0225] ethyleneglycol: 5% by mass

[0226] butylcarbitol: 3% by mass

[0227] N,N-bis(hydroxyethyl)-2-aminoethane sulfonic acid: 35% by mass

[0228] Sodium hydroxide: 2.4% by mass

[0229] Olfin E1010 (manufactured by Nissin Chemical Industry Co., Ltd):0.5% by mass

[0230] Pure water: the balance

Example 5

[0231] After mixing the components below, an ink is prepared byfiltering with a membrane filter with a pore size of 5 μm.

[0232] Dispersed solution of self-dispersing pigment (IJX-266,manufactured by Cabot Corporation): 3% by mass

[0233] diethyleneglycol: 15% by mass

[0234] N,N-bis(hydroxyethyl)-2-aminoethane sulfonic acid: 3% by mass

[0235] Sodium hydroxide: 0.01% by mass

[0236] Olfin E1010 (manufactured by Nissin Chemical Industry Co., Ltd):0.2% by mass

[0237] Pure water: the balance

Example 6

[0238] After mixing the components below, an ink is prepared byfiltering with a membrane filter with a pore size of 5 μm.

[0239] C.I. Acid Blue-9: 6% by mass

[0240] Diethyleneglycol: 15% by mass

[0241] N,N-bis(hydroxyethyl)glycine: 10% by mass

[0242] Sodium hydroxide: 0.3% by mass

[0243] Olfin E1010 (manufactured by Nissin Chemical Industry Co., Ltd.):0.05% by mass

[0244] Pure water: the balance

Example 7

[0245] After mixing the components below, an ink is prepared byfiltering with a membrane filter with a pore size of 5 μm.

[0246] Food black 2 (manufactured by Zeneca Co.): 5% by mass

[0247] Diethyleneglycol: 17% by mass

[0248] Tris(2-hydroxyethyl)amine: 10% by mass

[0249] Olfin E1010 (manufactured by Nissin Chemical Industry Co., Ltd.):1% by mass

[0250] Pure water: the balance

Example 8

[0251] After mixing the components below, an ink is prepared byfiltering with a membrane filter with a pore size of 5 μm.

[0252] C.I. Acid Blue-9: 6% by mass

[0253] Diethyleneglycol: 5% by mass

[0254] Tris(2-hydroxyethyl)amine: 30% by mass

[0255] Olfin E1010 (manufactured by Nissin Chemical Industry Co., Ltd.):1% by mass

[0256] Pure water: the balance

Example 9

[0257] After mixing the components below, an ink is prepared byfiltering with a membrane filter with a pore size of 5 μm.

[0258] Dispersed solution of self-dispersing pigment (IJX-253,manufactured by Cabot Corporation): 3% by mass

[0259] Diethyleneglycol: 10% by mass

[0260] 2,2-bis(hydroxymethyl)-2,2,′,2″-nitrilotriethanol: 20% by mass

[0261] Olfin E1010 (manufactured by Nissin Chemical Industry Co., Ltd.):1% by mass

[0262] Pure water: the balance

Example 10

[0263] After mixing the components below, an ink is prepared byfiltering with a membrane filter with a pore size of 5 μm.

[0264] Dispersed solution of self-dispersing pigment (CAB-o-JET 300,manufactured by Cabot Corporation): 3% by mass

[0265] Glycerin: 25% by mass

[0266] N,N-bis(hydroxyethyl)-2-aminoethane sulfonic acid: 5% by mass

[0267] Sodium hydroxide: 0.3% by mass

[0268] Olfin E1010 (manufactured by Nissin Chemical Industry Co., Ltd.):1% by mass

[0269] Pure water: the balance

Example 11

[0270] After mixing the components below, an ink is prepared byfiltering with a membrane filter with a pore size of 5 μm.

[0271] Dispersed solution of self-dispersing pigment (IJX-253,manufactured by Cabot Corporation): 3% by mass

[0272] Glycerin: 5% by mass

[0273] N,N-bis(hydroxyethyl)-2-aminoethane sulfonic acid: 30% by mass

[0274] Sodium hydroxide: 2.4% by mass

[0275] Olfin E1010 (manufactured by Nissin Chemical Industry Co., Ltd.):1% by mass

[0276] Pure water: the balance

Comparative Example 1

[0277] After mixing the components below, an ink is prepared byfiltering with a membrane filter with a pore size of 5 μm.

[0278] Dispersed solution of self-dispersing pigment (CAB-O-JET 300,manufactured by Cabot Corporation): 3% by mass

[0279] Diethyleneglycol: 10% by mass

[0280] Butylcarbitol: 10% by mass

[0281] E215 (manufactured by Nippon Oil & Fats Co., Ltd.): 1% by mass

[0282] Pure water: the balance

Comparative Example 2

[0283] After mixing the components below, an ink is prepared byfiltering with a membrane filter with a pore size of 5 μm.

[0284] Dispersed solution of self-dispersing pigment (IJX 444,manufactured by Cabot Corporation): 3% by mass

[0285] Diethyleneglycol: 15% by mass

[0286] Glycine: 15% by mass

[0287] Sodium hydroxide: 1.5% by mass

[0288] Olfin E1010 (manufactured by Nissin Chemical Industry Co., Ltd.):0.2% by mass

[0289] Pure water: the balance

Comparative Example 3

[0290] After mixing the components below, an ink is prepared byfiltering with a membrane filter with a pore size of 5 μm.

[0291] Dispersed solution of self-dispersing pigment (IJX 253,manufactured by Cabot Corporation): 3% by mass

[0292] Diethyleneglycol: 5% by mass

[0293] Glycine: 15% by mass

[0294] Olfin E1010 (manufactured by Nissin Chemical Industry Co., Ltd.):0.05% by mass

[0295] Pure water: the balance

Comparative Example 4

[0296] After mixing the components below, an ink is prepared byfiltering with a membrane filter with a pore size of 5 μm.

[0297] Dispersed solution of self-dispersing pigment (IJX 253,manufactured by Cabot Corporation): 3% by mass

[0298] Diethyleneglycol: 5% by mass

[0299] Betaine: 15% by mass

[0300] Olfin E10110 (manufactured by Nissin Chemical Industry Co.,Ltd.): 0.5% by mass

[0301] Pure water: the balance

Comparative Example 5

[0302] After mixing the components below, an ink is prepared byfiltering with a membrane filter with a pore size of 5 μm.

[0303] C.I. Direct Blue-199: 3% by mass

[0304] Glycerin: 30% by mass

[0305] Tris(2-hydroxyethyl)amine: 5% by mass

[0306] Olfin E1010 (manufactured by Nissin Chemical Industry Co., Ltd.):2% by mass

[0307] Pure water: the balance

Comparative Example 6

[0308] After mixing the components below, an ink is prepared byfiltering with a membrane filter with a pore size of 5 μm.

[0309] C.I. Direct Blue-199: 3% by mass

[0310] Glycerin: 3% by mass

[0311] Tris(2-hydroxyethyl)amine: 35% by mass

[0312] Olfin E1010 (manufactured by Nissin Chemical Industry Co., Ltd.):2% by mass

[0313] Pure water: the balance

[0314] <Evaluation>

[0315] Curling, image density, clogging and surface tension with respectto Examples 1 to 11 and Comparative Examples 1 to 6 are measured andevaluated. The results are shown in Table 1 together with the meltingpoint or decomposition point of the amine added.

[0316] The numerical values marked by “dec” in the column of “meltingpoint or decomposition point of the amine” in Table 1 denote thedecomposition point. TABLE 1 Ink Amine Melting or content decomposi-Surface Result of evaluation (mass tion point of tension Image Clog- %)amine (° C.) (mN/m) Curling density ging Example 1 15 190 (dec) 33 a a aExample 2 10 156 33 a a a Example 3 15 190 (dec) 32 a a a Example 4 35156 28 a a b Example 5 3 156 36 b b a Example 6 10 190 (dec) 42 a a aExample 7 10  21 32 a b a Example 8 30  21 36 a a a Example 9 20 104 30a a a  Example 10 5 156 35 a a a  Example 11 30 156 32 a a a Comparative0 — 37 d d b example 1 Comparative 15 290 (dec) 32 d b c example 2Comparative 15 290 (dec) 42 d b d example 3 Comparative 15 310 (dec) 33d d c example 4 Comparative 5  21 28 d d b example 5 Comparative 35  2128 a c d example 6

[0317] The evaluation criteria of curl, image density, clogging andsurface tension in Table 1 are as follows.

[0318] (1) Measurement of Curling

[0319] The inks manufactured in each example and comparative example arefilled in a recording head of a commercially available ink jet printerWork Center B900N (manufactured by Fuji Xerox Co., Ltd.). An arectangular monochromatic solid image with a length of 270 mm and awidth of 190 mm is printed on a commercially available regular paper P(A4 seize, 297 mm×210 mm, manufactured by Fuji Xerox Office Supply Co.,Ltd.). The height of warp of the paper is measured after placing it onan office desk at 23° C. and 55% RH. The height of warp denotes avertical distance from the desk plane to the edge of the paper when theedge is lifted up from the surface of the desk by curling.

[0320] Evaluation criteria are as follows:

[0321] a: warp height, less than 20 mm

[0322] b: warp height, 20 mm or more and less than 40 mm

[0323] c: warp height, 40 mm or more and less than 60 mm

[0324] d: warp height, 60 mm or more, or the paper is rounded into acylinder

[0325] (2) Image Density

[0326] The image density at the solid printing region of the printedmatter used in the curl test above is measured with a photo-densitometerX-Rite MODEL 404 (manufactured by X-Rite Co.). Evaluation criteria areas follows:

[0327] a: optical density, 1.30 or more

[0328] b: optical density, 1.20 or more and less than 1.30

[0329] c: optical density, 1.10 or more and less than 1.20

[0330] d: optical density, less than 1.10

[0331] (3) Clogging

[0332] After continuously printing 10 sheets of solid images under thesame condition as in the measurement of curl, nozzle check patterns areoutput to confirm clog of the nozzle and occurrence of directionalerror. Evaluation criteria are as follows:

[0333] a: no clogging and no directional error

[0334] b: no clogging, and incidence of the directional error is lessthan 1%.

[0335] c: incidence of clogging is less than 1% of all the nozzles, andincidence of the directional error is less than 3% of all the nozzle

[0336] d: incidence of clogging is 1% or more of all the nozzles, andincidence of the directional error is 3% or more of all the nozzle

[0337] (4) Surface Tension

[0338] The surface tension is measured at 23° C. and 55% RH usingWhilhelmy surface tension meter (manufactured by Kyowa Interface ScienceCo., Ltd.).

[0339] As described in the above, in a first major aspect, the inventionprovides an ink jet ink composition, ink set, ink jet treatment liquid,ink jet recording method and ink jet recording apparatus that enables torelieve or suppress curling of the recording medium and clogging of thenozzle.

[0340] In a second major aspect, the invention provides an ink jet inkcomposition, ink jet treatment liquid, ink jet recording method and inkjet recording apparatus that enables to relieve or suppress curling ofthe recording medium and clogging of the nozzle while the image densityis further improved.

What is claimed is:
 1. An ink jet ink composition comprising at leastwater, a colorant and a water-soluble organic solvent, wherein the inkjet ink composition comprises at least one amine compound represented bythe following formula (1) in a range of 10 to 30% by mass:

wherein the amine compound represented by the formula (1) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁, R₂ and R₃ in the formula (1) comprises a hydrocarbongroup having a hydroxyl group; and none of the three substituentscontain an alkyl group having at its terminal either one of —CO₂M and—SO₃M in which M represents an atom or an atomic group selected fromhydrogen, an alkali metal, an alkaline earth metal, an ammonium groupand an organic amine group.
 2. An ink jet ink composition according toclaim 1, wherein in the formula (1), two of the three substituentsrepresented by R₁, R₂ and R₃ comprise a hydrocarbon group having ahydroxyl group.
 3. An ink jet ink composition according to claim 1,wherein the hydroxyl group is positioned at the terminal of thehydrocarbon group having the hydroxyl group.
 4. An ink jet inkcomposition according to claim 1, wherein the hydrocarbon group havingthe hydroxyl group comprises a hydroxyalkyl group.
 5. An ink jet inkcomposition according to claim 1, wherein the hydrocarbon group havingthe hydroxyl group comprises a linear hydroxyalkyl group having 1 to 5carbon atoms.
 6. An ink jet ink composition according to claim 1,wherein a melting point or decomposition point of the amine compound is50° C. or more.
 7. An ink jet ink composition according to claim 1,wherein a surface tension of the ink composition is 40 mN/m or less. 8.An ink jet ink composition comprising at least water, a colorant and awater-soluble organic solvent, wherein the ink jet ink compositioncomprises at least one amine compound represented by the followingformula (2):

wherein the amine compound represented by the formula (2) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁′, R₂′ and R₃′ in the formula (2) comprises ahydrocarbon group having a hydroxyl group; and at least one of the threesubstituents comprises a hydrocarbon group containing an alkyl grouphaving at its terminal either one of —CO₂M and —SO₃M in which Mrepresents an atom or an atomic group selected from hydrogen, an alkalimetal, an alkaline earth metal, an ammonium group and an organic aminegroup.
 9. An ink jet ink composition according to claim 8, wherein acontent of the amine compound is in a range of 5 to 30% by mass.
 10. Anink jet ink composition according to claim 8, wherein the amine compoundis selected from the group consisting of N,N-bis(hydroxyalkyl)glycinederivatives and N,N-bis(hydroxyalkyl)-2-aminoethanesulfonic acidderivatives.
 11. An ink jet ink composition according to claim 8,wherein a melting point or decomposition point of the amine compound is50° C. or more.
 12. An ink jet ink composition according to claim 8,wherein a surface tension of the ink composition is 40 mN/m or less. 13.An ink jet recording method comprising forming an image by adhering anink jet ink composition comprising at least water, a colorant and awater soluble organic solvent, to a recording medium, wherein the inkjet ink composition comprises at least one amine compound represented bythe following formula (1) in a range of 10 to 30% by mass:

wherein the amine compound represented by the formula (1) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁, R₂ and R₃ in the formula (1) comprises a hydrocarbongroup having a hydroxyl group; and none of the three substituentscontain an alkyl group having at its terminal either one of —CO₂M and—SO₃M in which M represents an atom or an atomic group selected fromhydrogen, an alkali metal, an alkaline earth metal, an ammonium groupand an organic amine group.
 14. An ink jet recording method comprisingforming an image by adhering an ink jet ink composition comprising atleast water, a colorant and a water soluble organic solvent, to arecording medium, wherein the ink jet ink composition comprises at leastone amine compound represented by the following formula (2):

wherein the amine compound represented by the formula (2) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁′, R₂′ and R₃′ in the formula (2) comprises ahydrocarbon group having a hydroxyl group; and at least one of the threesubstituents comprises a hydrocarbon group containing an alkyl grouphaving at its terminal either one of —CO₂M and —SO₃M in which Mrepresents an atom or an atomic group selected from hydrogen, an alkalimetal, an alkaline earth metal, an ammonium group and an organic aminegroup.
 15. An ink jet recording apparatus comprising at least arecording head including a liquid ejection surface having a nozzle forejecting a liquid, and a recording medium transfer section fortransferring a recording medium in one direction while the recordingmedium faces the liquid ejection surface and a shortest distance betweenthe recording medium and the liquid ejection surface is constantlymaintained, wherein: during printing,an image is formed by ejecting theliquid onto a surface of the recording medium from the liquid ejectionsurface while moving the recording head in a direction substantiallyperpendicular to the transfer direction of the recording medium; an inkjet ink composition comprising at least water, a colorant and a watersoluble organic solvent is used as the liquid; and the ink jet inkcomposition comprises at least one amine compound represented by thefollowing formula (1) in a range of 10 to 30% by mass,

wherein the amine compound represented by the formula (1) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁, R₂ and R₃ in the formula (1) comprises a hydrocarbongroup having a hydroxyl group; and none of the three substituentscontain an alkyl group having at its terminal either one of —CO₂M and—SO₃M in which M represents an atom or an atomic group selected fromhydrogen, an alkali metal, an alkaline earth metal, an ammonium groupand an organic amine group.
 16. An ink jet recording apparatus accordingto claim 15, wherein the shortest distance between the liquid ejectionsurface and the recording medium is in a range of 1.0 mm to 2.0 mm, anda largest length of the liquid ejection surface in the recording mediumtransfer direction is 2.54 cm or more.
 17. An ink jet recordingapparatus comprising at least a recording head including a liquidejection surface having a nozzle for ejecting a liquid, and a recordingmedium transfer section for transferring a recording medium in onedirection while the recording medium faces the liquid ejection surfaceand a shortest distance between the recording medium and the liquidejection surface is constantly maintained, wherein: during printing, animage is formed by ejecting the liquid onto a surface of the recordingmedium from the liquid ejection surface while moving the recording headin a direction substantially perpendicular to the transfer direction ofthe recording medium; an ink jet ink composition comprising at leastwater, a colorant and a water soluble organic solvent is used as theliquid; and the ink jet ink composition comprises at least one aminecompound represented by the following formula (2),

wherein the amine compound represented by the formula (2) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁′, R₂′ and R₃′ in the formula (2) comprises ahydrocarbon group having a hydroxyl group; and at least one of the threesubstituents comprises a hydrocarbon group containing an alkyl grouphaving at its terminal either one of —CO₂M and —SO₃M in which Mrepresents an atom or an atomic group selected from hydrogen, an alkalimetal, an alkaline earth metal, an ammonium group and an organic aminegroup.
 18. An ink jet recording apparatus according to claim 17, whereinthe shortest distance between the liquid ejection surface and therecording medium is in a range of 1.0 mm to 2.0 mm, and a largest lengthof the liquid ejection surface in the recording medium transferdirection is 2.54 cm or more.
 19. An ink set comprising at least twoinks which each comprise water, a colorant and a water soluble organicsolvent, wherein at least one ink in the ink set comprises at least oneamine compound represented by the following formula (1) in a range of 10to 30% by mass:

wherein the amine compound represented by the formula (1) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁, R₂ and R₃ in the formula (1) comprises a hydrocarbongroup having a hydroxyl group; and none of the three substituentscontain an alkyl group having at its terminal either one of —CO₂M and—SO₃M in which M represents an atom or an atomic group selected fromhydrogen, an alkali metal, an alkaline earth metal, an ammonium groupand an organic amine group.
 20. An ink set comprising at least two inkswhich each comprise water, a colorant and a water soluble organicsolvent, wherein at least one ink in the ink set comprises at least oneamine compound represented by the following formula (2):

wherein the amine compound represented by the formula (2) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁′, R₂′ and R₃′ in the formula (2) comprises ahydrocarbon group having a hydroxyl group; and at least one of the threesubstituents comprises a hydrocarbon group containing an alkyl grouphaving at its terminal either one of —CO₂M and —SO₃M in which Mrepresents an atom or an atomic group selected from hydrogen, an alkalimetal, an alkaline earth metal, an ammonium group and an organic aminegroup.
 21. An ink jet recording method comprising forming an image byusing an ink set containing at least two inks comprising at least water,a colorant and a water soluble organic solvent, and by adhering an inkof the ink set to a recording medium, wherein at least one ink of theink set comprises at least one amine compound represented by thefollowing formula (1) in a range of 10 to 30% by mass:

wherein the amine compound represented by the formula (1) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁, R₂ and R₃ in the formula (1) comprises a hydrocarbongroup having a hydroxyl group; and none of the three substituentscontain an alkyl group having at its terminal either one of —CO₂M and—SO₃M in which M represents an atom or an atomic group selected fromhydrogen, an alkali metal, an alkaline earth metal, an ammonium groupand an organic amine group.
 22. An ink jet recording method comprisingforming an image by using an ink set containing at least two inkscomprising at least water, a colorant and a water soluble organicsolvent, and by adhering an ink of the ink set to a recording medium,wherein at least one ink of the ink set comprises at least one aminecompound represented by the following formula (2):

wherein the amine compound represented by the formula (2) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁′, R₂′ and R₃′ in the formula (2) comprises ahydrocarbon group having a hydroxyl group; and at least one of the threesubstituents comprises a hydrocarbon group containing an alkyl grouphaving at its terminal either one of —CO₂M and —SO₃M in which Mrepresents an atom or an atomic group selected from hydrogen, an alkalimetal, an alkaline earth metal, an ammonium group and an organic aminegroup.
 23. An ink jet recording apparatus comprising at least arecording head including a liquid ejection surface having at least twonozzles for independently ejecting at least two liquids, and a recordingmedium transfer section for transferring a recording medium in onedirection while the recording medium faces the liquid ejection surfaceand a shortest distance between the recording medium and the liquidejection surface is constantly maintained, wherein: during printing, animage is formed by ejecting the at least two liquids onto a surface ofthe recording medium from the liquid ejection surface while moving therecording head in a direction substantially perpendicular to thetransfer direction of the recording medium; an ink set comprising atleast two inks comprising at least water, a colorant and a water solubleorganic solvent is used as the at least two liquids; and at least oneink in the ink set comprises at least one amine compound represented bythe following formula (1) in a range of 10 to 30% by mass,

wherein the amine compound represented by the formula (1) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁, R₂ and R₃ in the formula (1) comprises a hydrocarbongroup having a hydroxyl group; and none of the three substituentscontain an alkyl group having at its terminal either one of —CO₂M and—SO₃M in which M represents an atom or an atomic group selected fromhydrogen, an alkali metal, an alkaline earth metal, an ammonium groupand an organic amine group.
 24. An ink jet recording apparatuscomprising at least a recording head including a liquid ejection surfacehaving at least two nozzles for independently ejecting at least twoliquids, and a recording medium transfer section for transferring arecording medium in one direction while the recording medium faces theliquid ejection surface and a shortest distance between the recordingmedium and the liquid ejection surface is constantly maintained,wherein: during printing, an image is formed by ejecting the at leasttwo liquids onto a surface of the recording medium from the liquidejection surface while moving the recording head in a directionsubstantially perpendicular to the transfer direction of the recordingmedium; an ink set comprising at least two inks comprising at leastwater, a colorant and a water soluble organic solvent is used as the atleast two liquids; and at least one ink in the ink set comprises atleast one amine compound represented by the following formula (2):

wherein the amine compound represented by the formula (2) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁′, R₂′ and R₃′ in the formula (2) comprises ahydrocarbon group having a hydroxyl group; and at least one of the threesubstituents comprises a hydrocarbon group containing an alkyl grouphaving at its terminal either one of —CO₂M and —SO₃M in which Mrepresents an atom or an atomic group selected from hydrogen, an alkalimetal, an alkaline earth metal, an ammonium group and an organic aminegroup.
 25. A colorless ink jet treatment liquid which is used togetherwith an ink jet ink composition comprising at least water, a colorantand a water soluble organic solvent, during printing, and comprises atleast water and a water soluble organic solvent, wherein the ink jettreatment liquid comprises at least one amine compound represented bythe following formula (1) in a range of 10 to 30% by mass:

wherein the amine compound represented by the formula (1) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁, R₂ and R₃ in the formula (1) comprises a hydrocarbongroup having a hydroxyl group; and none of the three substituentscontain an alkyl group having at its terminal either one of —CO₂M and—SO₃M in which M represents an atom or an atomic group selected fromhydrogen, an alkali metal, an alkaline earth metal, an ammonium groupand an organic amine group.
 26. A colorless ink jet treatment liquidwhich is used together with an ink jet ink composition comprising atleast water, a colorant and a water soluble organic solvent, duringprinting, and comprises at least water and a water soluble organicsolvent, wherein the ink jet treatment liquid comprises at least oneamine compound represented by the following formula (2):

wherein the amine compound represented by the formula (2) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁′, R₂′ and R₃′ in the formula (2) comprises ahydrocarbon group having a hydroxyl group; and at least one of the threesubstituents comprises a hydrocarbon group containing an alkyl grouphaving at its terminal either one of —CO₂M and —SO₃M in which Mrepresents an atom or an atomic group selected from hydrogen, an alkalimetal, an alkaline earth metal, an ammonium group and an organic aminegroup.
 27. An ink jet recording method comprising forming an image byadhering an ink jet ink composition comprising at least water, acolorant and a water soluble organic solvent, and a colorless ink jettreatment liquid comprising at least water and a water soluble organicsolvent, to approximately the same region on a recording medium, whereinthe ink jet treatment liquid comprises at least one amine compoundrepresented by the following formula (1) in a range of 10 to 30% bymass:

wherein the amine compound represented by the formula (1) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁, R₂ and R₃ in the formula (1) comprises a hydrocarbongroup having a hydroxyl group; and none of the three substituentscontain an alkyl group having at its terminal either one of —CO₂M and—SO₃M in which M represents an atom or an atomic group selected fromhydrogen, an alkali metal, an alkaline earth metal, an ammonium groupand an organic amine group.
 28. An ink jet recording method comprisingforming an image by adhering an ink jet ink composition comprising atleast water, a colorant and a water soluble organic solvent, and acolorless ink jet treatment liquid comprising at least water and a watersoluble organic solvent, to approximately the same region on a recordingmedium, wherein the ink jet treatment liquid comprises at least oneamine compound represented by the following formula (2):

wherein the amine compound represented by the formula (2) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁′, R₂′ and R₃′ in the formula (2) comprises ahydrocarbon group having a hydroxyl group; and at least one of the threesubstituents comprises a hydrocarbon group containing an alkyl grouphaving at its terminal either one of —CO₂M and —SO₃M in which Mrepresents an atom or an atomic group selected from hydrogen, an alkalimetal, an alkaline earth metal, an ammonium group and an organic aminegroup.
 29. An ink jet recording apparatus comprising at least arecording head including a liquid ejection surface comprising at leasttwo nozzles for independently ejecting at least two liquids, and arecording medium transfer section for transferring a recording medium inone direction while the recording medium faces the liquid ejectionsurface and a shortest distance between the recording medium and theliquid ejection surface is constantly maintained, wherein: duringprinting, an image is formed by ejecting the at least two liquids onto asurface of the recording medium from the liquid ejection surface whilemoving the recording head in a direction substantially perpendicular tothe transfer direction of the recording medium; an ink jet inkcomposition comprising at least water, a colorant and a water solubleorganic solvent, and a colorless ink jet treatment liquid comprising atleast water and a water soluble organic solvent are used as the at leasttwo liquids; and the ink jet treatment liquid comprises at least oneamine compound represented by the following formula (1) in a range of 10to 30% by mass:

wherein the amine compound represented by the formula (1) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁, R₂ and R₃ in the formula (1) comprises a hydrocarbongroup having a hydroxyl group; and none of the three substituentscontain an alkyl group having at its terminal either one of —CO₂M and—SO₃M in which M represents an atom or an atomic group selected fromhydrogen, an alkali metal, an alkaline earth metal, an ammonium groupand an organic amine group.
 30. An ink jet recording apparatuscomprising at least a recording head including a liquid ejection surfacecomprising at least two nozzles for independently ejecting at least twoliquids, and a recording medium transfer section for transferring arecording medium in one direction while the recording medium faces theliquid ejection surface and a shortest distance between the recordingmedium and the liquid ejection surface is constantly maintained,wherein: during printing, an image is formed by ejecting the at leasttwo liquids onto a surface of the recording medium from the liquidejection surface while moving the recording head in a directionsubstantially perpendicular to the transfer direction of the recordingmedium; an ink jet ink composition comprising at least water, a colorantand a water soluble organic solvent, and a colorless ink jet treatmentliquid comprising at least water and a water soluble organic solvent areused as the at least two liquids; and, the ink jet treatment liquidcomprises at least one amine compound represented by the followingformula (2),

wherein the amine compound represented by the formula (2) is any one ofprimary to tertiary amine compounds; at least one of three substituentsrepresented by R₁′, R₂′ and R₃′ in the formula (2) comprises ahydrocarbon group having a hydroxyl group; and at least one of the threesubstituents comprises a hydrocarbon group containing an alkyl grouphaving at its terminal either one of —CO₂M and —SO₃M in which Mrepresents an atom or an atomic group selected from hydrogen, an alkalimetal, an alkaline earth metal, an ammonium group and an organic aminegroup.